CO2 is most definitely produced during the production of propane and natural gas. CO2 and water vapor are the primary combustion products which is why burning fossil fuels leads to global warming.
I think you are confusing CO2 and CO. Under non-ideal situations, combustion also produces small amounts of CO in addition to CO2. CO is very poisonous which is why there is a CO (not CO2!) detector in your camper.
I think you are confusing CO2 and CO. Under non-ideal situations, combustion also produces small amounts of CO in addition to CO2. CO is very poisonous which is why there is a CO (not CO2!) detector in your camper.